A PARAMETRIC STUDY OF GRAPHENE SYNTHESIS BY CHEMICAL VAPOR DEPOSITION AND GRAPHENE TRANSFER ON SUBSTRATES

Abstract

Chemical vapor deposition (CVD) is the major method to synthesize high-quality graphene (i.e. large size, low resistance and high transparency) for electronics applications. In this research, 2 factors that affect the quality of the CVD-grown graphene have been investigated: the flow rate of methane gas and the substrate type whereas 3 different flow rates of methane gas: 40, 60, 80 sccm and 3 substrate types: nickel film, copper film and copper foil were used. According to the results from optical microscopy and raman spectroscopy, it was found that the graphene synthesized using the methane flow rate of 60 sccm and the copper foil substrate had the best quality whereas the synthesized graphene mostly consisted of uniform monolayer graphene with large grain sizes. In the second part, the transfer of the synthesized graphene films onto silicon dioxide and polydimethylsiloxane (PDMS) substrates by using improved transfer methods have been studied. It was found that graphene could be successfully transferred onto silicon dioxide substrates by the scooping up method and the method that utilized PDMS stamp with dry transfer whereas the sheet resistance was approximately 1,000 Ω/□. Furthermore, a new method for graphene transfer onto flexible PDMS substrates has been successfully developed by utilizing SU-8 as an adhesion layer whereas the measured sheet resistance was 1,139 Ω/□. Finally, electrodes fabricated from multi-layer graphene have been developed. The measured sheet resistances were 850.49, 389.78 and 294.61 Ω/□, respectively whereas the measured transparency were 98%, 93% and 90%, respectively.